1. Field of the Invention
This is a continuation of International Application PCT/EP97/06200 filed Nov. 7, 1997, of the same inventor.
The invention relates to a tablet tester.
Tablet testers are apparatuses which are used mainly in the pharmaceutical industry or in science and research. Since medicaments which are administered in tablet form must in some cases meet very precise quality and quantity requirements, parameters of the respective tablets which are determined at least on random samples are measured.
2. Discussion of Relevant Art
Apparatuses which accommodate a plurality of testing or measuring stations and in which tablets are transported from a storage container to the individual station are known for such measuring processes. An example of such an apparatus is the combination tablet tester "Multicheck" from ERWEKA, D-63150 Heusenstamm. It permits the automatic or computer-controlled measurement of weight, thickness, diameter and hardness of individual tablets, which have to be delivered in succession from a storage container.
However, it is precisely the individual delivery of tablets that is a problem in such apparatuses. Thus, the very company mentioned is attempting, by means of EP-B1-170670, to describe a particularly suitable transport means for tablets within such a combination tablet tester. The transport means is designed in such a way that a rake having V-shaped forks pushes the tablets over a guide track which has exactly dimensioned holes through which unsuitable tablets are intended to fall. This apparatus thus forms a sort of sieve, the size of the tablets and their (accidental) position relative to the forks determining whether they are transported further or fall through the holes. There remains therefore an uncertainty which may lead to delays in measurement or incorrect measurements. Apart from this, the solution offered by ERWEKA may be susceptible to faults in the region in which the tablets are fed to the rake or cannot always ensure that the tablets also reach the required position and enter the rake individually. For some of the individual measuring stations, it is in fact important whether the tablets are vertical or horizontal and whether they are delivered longitudinally or crosswise. If more than one tablet is present in a fork of the rake, these tablets cannot be measured or the result is a rejected measurement.
On the other hand, the rejection of tablet fragments before passage through the measuring stations is not ensured in the known apparatus, so that here too incorrect measurements can occur.
There is thus no satisfactory, universal technique in this context particularly for different tablet shapes. This leads to the necessity of conversions for different tablet shapes or to a loss of time during measurement.
In an attempt to improve the situation, Norbert Kramer of D-6100 Darmstadt has provided a relatively complicated isolating apparatus having baffles for tablets, which is described in DE-C2-3711827. His apparatus is intended to isolate tablets over particularly short distances. However, this description offers no solution for further transport to the individual measuring stations. Furthermore, the problem of positioning and of the rejection of tablet fragments is not solved by Kramer.
Another manufacturer, Elisabeth Hata, uses Kramer's isolating apparatus but without its baffles, which leads to adequate isolation in the case of relatively large tablets but to trouble-prone isolation in the case of smaller tablets.